.\" Copyright (c) 1983, 1991, 1993
.\"	The Regents of the University of California.  All rights reserved.
.\"
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.\" modification, are permitted provided that the following conditions
.\" are met:
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.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\" 3. All advertising materials mentioning features or use of this software
.\"    must display the following acknowledgement:
.\"	This product includes software developed by the University of
.\"	California, Berkeley and its contributors.
.\" 4. Neither the name of the University nor the names of its contributors
.\"    may be used to endorse or promote products derived from this software
.\"    without specific prior written permission.
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\"
.\"     @(#)rename.2	8.1 (Berkeley) 6/4/93
.\"	$Id: rename.2,v 1.1.1.1 2006/05/30 06:12:12 hhzhou Exp $
.\"
.Dd June 4, 1993
.Dt RENAME 2
.Os BSD 4.2
.Sh NAME
.Nm rename
.Nd change the name of a file
.Sh SYNOPSIS
.Fd #include <stdio.h>
.Ft int
.Fn rename "const char *from" "const char *to"
.Sh DESCRIPTION
.Fn Rename
causes the link named
.Fa from
to be renamed as
.Fa to .
If 
.Fa to
exists, it is first removed.
Both 
.Fa from
and
.Fa to
must be of the same type (that is, both directories or both
non-directories), and must reside on the same file system.
.Pp
.Fn Rename
guarantees that an instance of
.Fa to
will always exist, even if the system should crash in
the middle of the operation.
.Pp
If the final component of
.Fa from
is a symbolic link,
the symbolic link is renamed,
not the file or directory to which it points.
.\".Sh CAVEAT
.\"The system can deadlock if a loop in the file system graph is present.
.\"This loop takes the form of an entry in directory
.\".Ql Pa a ,
.\"say
.\".Ql Pa a/foo ,
.\"being a hard link to directory
.\".Ql Pa b ,
.\"and an entry in
.\"directory
.\".Ql Pa b ,
.\"say
.\".Ql Pa b/bar ,
.\"being a hard link
.\"to directory
.\".Ql Pa a .
.\"When such a loop exists and two separate processes attempt to
.\"perform
.\".Ql rename a/foo b/bar
.\"and
.\".Ql rename b/bar a/foo ,
.\"respectively, 
.\"the system may deadlock attempting to lock
.\"both directories for modification.
.\"Hard links to directories should be
.\"replaced by symbolic links by the system administrator.
.Sh RETURN VALUES
A 0 value is returned if the operation succeeds, otherwise
.Fn rename
returns -1 and the global variable 
.Va errno
indicates the reason for the failure.
.Sh ERRORS
.Fn Rename
will fail and neither of the argument files will be
affected if:
.Bl -tag -width ENAMETOOLONG
.It Bq Er ENAMETOOLONG
A component of either pathname exceeded 255 characters,
or the entire length of either path name exceeded 1023 characters.
.It Bq Er ENOENT
A component of the
.Fa from
path does not exist,
or a path prefix of
.Fa to
does not exist.
.It Bq Er EACCES
A component of either path prefix denies search permission.
.It Bq Er EACCES
The requested link requires writing in a directory with a mode
that denies write permission.
.It Bq Er EPERM
The directory containing
.Fa from
is marked sticky,
and neither the containing directory nor
.Fa from
are owned by the effective user ID.
.It Bq Er EPERM
The
.Fa to
file exists,
the directory containing
.Fa to
is marked sticky,
and neither the containing directory nor
.Fa to
are owned by the effective user ID.
.It Bq Er ELOOP
Too many symbolic links were encountered in translating either pathname.
.It Bq Er ENOTDIR
A component of either path prefix is not a directory.
.It Bq Er ENOTDIR
.Fa from
is a directory, but
.Fa to
is not a directory.
.It Bq Er EISDIR
.Fa to
is a directory, but
.Fa from
is not a directory.
.It Bq Er EXDEV
The link named by
.Fa to
and the file named by
.Fa from
are on different logical devices (file systems).  Note that this error
code will not be returned if the implementation permits cross-device
links.
.It Bq Er ENOSPC
The directory in which the entry for the new name is being placed
cannot be extended because there is no space left on the file
system containing the directory.
.It Bq Er EDQUOT
The directory in which the entry for the new name
is being placed cannot be extended because the
user's quota of disk blocks on the file system
containing the directory has been exhausted.
.It Bq Er EIO
An I/O error occurred while making or updating a directory entry.
.It Bq Er EROFS
The requested link requires writing in a directory on a read-only file
system.
.It Bq Er EFAULT
.Em Path
points outside the process's allocated address space.
.It Bq Er EINVAL
.Fa From
is a parent directory of
.Fa to ,
or an attempt is made to rename
.Ql \&.
or
.Ql \&.. .
.It Bq Er ENOTEMPTY
.Fa To
is a directory and is not empty.
.El
.Sh SEE ALSO
.Xr open 2 ,
.Xr symlink 7
.Sh STANDARDS
The
.Fn rename
function call is expected to conform to 
.St -p1003.1-90 .
